I think you're grossly exaggerating the conceptual differences between low and high elo:
You appear to have this understanding that high elo input is irrelevant to low elo meta/improvement, but I don't think you have the relevant information to reach that conclusion. The only difference between low and high elo players anyone can say with certainty is that low elo players have not been to high elo, and high elo players can have gone through low elo. High elo can have seen two sides of the picture, you can only have seen one.
You seem to have this understanding that climbing out of lower elos is more of a gimmick than actually improving as a player. You're looking for the cheatcode to low elo rather than doing something much simpler: Improve as a player. You don't need some special 1v9 to climb out of lower elos, being able to 5v5 is more than enough.
Your arguments are attempts to find things that you happen to not be good at (or that you think you are 'good enough for your elo') and try to find ways to avoid them rather than confront them. Just because you can win lane on Vayne doesn't mean you can transition it. Hell, the fact that you win "8/10" lanes with her and still can't win when you are mid/late game focused shows how much you're missing in fundamentals.
"If you mess up, you are dead so she's too inconsistent for me" - this is literally what adc is at every elo. This isn't a problem with adc, this is a problem with you.
tl;dr: If you were to rewrite this post and replace S1/G5 with D5, all the low Diamond members of the community would agree with you (myself included). Really though that's just a joke. The reason I'm stuck in low-mid Diamond is the same reason you're stuck in low Gold - we don't have the game knowledge to improve yet. Pretending it's pick based or that those pesky Masters players have got it easy is an excuse: If I was better I'd be higher on the ladder.